The book is devoted to the physical properties of nonideal plasma, in which the effects of interparticle interactions are substantial. Such a plasma is usually compressed so strongly that it is called dense plasma. Interest in plasma studies has increased over the last 10 or 15 years, owing to the development of modern technology and sophisticated facilities whose oper ation is based on a high energy density. As a result of a recent sharp increase in the number of experimental and theoretical investigations, much interesting and reliable data on the properties of dense plasma have been obtained. The data are distributed in a rapidly growing number of original publications and reviews. This volume is a systematic treatment of the thermodynamics (ionization equilibrium, particle composition), charge transport properties (especially electric con ductivity), optical properties (peculiarities of continuous and discrete spectra), and collective modes (features and manifestations) of nonideal plasma. Theoretical models are considered along with the experimental data. The book is intended for the wide range of readers, including specialists in plasma physics and various researchers who need knowledge in this field.